Genetic characteristics of hepatitis B virus genotypes as a factor for interferon-induced HBeAg clearance

Virological and Clinical Characteristics of Hepatitis B Virus Genotype A

Hepatitis B virus (HBV) infection is one of the most prevalent chronic viral infections in humans. The overall prevalence of hepatitis B surface antigen (HBsAg) is reported to be 3.6%; however, it varies depending upon the geographic area. HBV is classified into ten genotypes (A through J) on the basis of an intergroup genomic divergence of > 8%. Specifically, HBV genotype A exhibits several unique virological and clinical characteristics and can be further classified into seven subtypes. Among them, subtype A2 or Ae (A2/[e]) is occasionally responsible for nosocomial infection and among homosexual males. Regarding virological factors, the G1896A precore mutation is rarely observed in genotype A as it would disrupt an essential stem-loop structure in the ε signal essential for pregenomic RNA packaging. HBV genotype A also harbors a 6-nucleotide C-terminal insertion in the hepatitis B-e antigen (HBeAg) precursor, resulting in a variable-length HBeAg protein product observed in serum of positive patients. These molecular traits likely contribute to the specific clinical presentation of genotype A-infected patients, such as mild acute hepatitis B (AHB), longer persistence of HBsAg positivity in AHB, and increased chronicity after AHB in adults. However, genotype A shows a better response to interferon than other genotypes in chronic hepatitis B patients. Here, we review the virological and clinical characteristics of HBV genotype A that will be useful in elucidating the association among persistent viral infection, host genetic factors, and treatment in future studies.

Long-term follow up of peginterferon-α-2a treatment of hepatitis B e-antigen (HBeAg) positive and HBeAg negative chronic hepatitis B patients in phase II and III studies

AIM

We analyzed the 5-year post-treatment response to peginterferon α-2a (PEG IFN-α-2a) in hepatitis B e-antigen (HBeAg) positive and negative chronic hepatitis B patients.

METHODS

One hundred and thirty-seven chronic hepatitis B (CHB) patients receiving 90 μg or 180 μg of PEG IFN-α-2a for 24 or 48 weeks in phase II or III studies were enrolled in the study, including 100 HBeAg positive patients and 37 HBeAg negative patients; 121 patients (88.4%) had genotype C.

RESULTS

Of the 137 patients, 94 received additional antiviral therapy because of viral reactivation and 43 did not receive any additional antiviral treatment during follow up. Five years upon PEG IFN-α-2a treatment, 32 patients (23.4%) who did not receive any additional antiviral agent after PEG IFN-α-2a therapy achieved a good response (normal serum alanine aminotransferase, low-level hepatitis B virus [HBV] DNA, and HBeAg negativity). Female sex and low HBV DNA levels by the end of treatment were independently associated with favorable 5-year post-treatment responses. Forty-eight-week administration of PEG IFN-α-2a showed a better response (26.4%) than 24-week administration (18.0%). Six patients (4.3%), four males and two females, cleared hepatitis B surface antigen (HBsAg) during the 5-year follow-up period.

CONCLUSION

The 48-week administration of PEG IFN-α-2a achieved better biochemical and virological responses than the 24-week administration, particularly in younger females. The 5-year post-treatment response rate was 23.4%; however, more than two-thirds of the patients received additional antiviral therapy because of viral reactivation after PEG IFN-α-2a treatment. HBsAg clearance was noted in six patients (4.3%). PEG IFN-α-2a is effective in young female patients.

Randomized phase II study of GS-4774 as a therapeutic vaccine in virally suppressed patients with chronic hepatitis B

BACKGROUND & AIMS

GS-4774 is a heat-inactivated, yeast-based, T-cell vaccine designed to elicit hepatitis B virus (HBV)-specific T-cell responses. We evaluated the safety, tolerability and efficacy of GS-4774 in patients with chronic HBV infection.

METHODS

In this phase II study, 178 patients with chronic HBV infection and no cirrhosis who were virally suppressed on an oral antiviral (OAV) for ⩾1year were randomized (1:2:2:2) to continue OAV alone or receive OAV plus GS-4774 2, 10, or 40 yeast units (YU) subcutaneously every 4weeks until week 20. OAV was continued for the remainder of the study. Efficacy was measured by decline in serum hepatitis B surface antigen (HBsAg) from baseline to week 24.

RESULTS

Baseline characteristics were similar across groups (mean age, 45-50years; male, 62-74%; Asian, 68-80%; hepatitis B e antigen (HBeAg)-positive, 24-26%; mean HBsAg, 2.5-3.1log10IU/ml). There were no significant differences between groups in mean HBsAg declines from baseline to week 24 or 48. Five HBeAg-positive patients receiving GS-4774 experienced HBeAg loss vs. none in the control group. Three GS-4774 40 YU-treated patients had HBsAg declines ⩾0.5log10IU/ml, but no patient experienced loss of serum HBsAg. No virologic breakthrough occurred. Injection site reactions were the most frequent adverse event (AE), and there were no treatment discontinuations.

CONCLUSIONS

GS-4774 was well tolerated, but did not provide significant reductions in serum HBsAg in virally suppressed patients with chronic hepatitis B. Efficacy of GS-4774 in treatment-naïve patients remains to be determined.

LAY SUMMARY

GS-4774 is a therapeutic vaccine designed to improve the immune response against hepatitis B virus (HBV) in patients who already have chronic infection with HBV. In this study, GS-4774 was safe and well tolerated in patients with chronic HBV infection receiving oral antiviral therapy, but did not result in a clinical benefit. Combination approaches with other agents, and evaluation in other populations of patients with HBV are ongoing to determine if GS-4774 might have a therapeutic benefit.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01943799.

Doubly Spliced RNA of Hepatitis B Virus Suppresses Viral Transcription via TATA-Binding Protein and Induces Stress Granule Assembly

The risk of liver cancer in patients infected with the hepatitis B virus (HBV) and their clinical response to interferon alpha therapy vary based on the HBV genotype. The mechanisms underlying these differences in HBV pathogenesis remain unclear. In HepG2 cells transfected with a mutant HBV(G2335A) expression plasmid that does not transcribe the 2.2-kb doubly spliced RNA (2.2DS-RNA) expressed by wild-type HBV genotype A, the level of HBV pregenomic RNA (pgRNA) was higher than that in cells transfected with an HBV genotype A expression plasmid. By using cotransfection with HBV genotype D and 2.2DS-RNA expression plasmids, we found that a reduction of pgRNA was observed in the cells even in the presence of small amounts of the 2.2DS-RNA plasmid. Moreover, ectopic expression of 2.2DS-RNA in the HBV-producing cell line 1.3ES2 reduced the expression of pgRNA. Further analysis showed that exogenously transcribed 2.2DS-RNA inhibited a reconstituted transcription in vitro. In Huh7 cells ectopically expressing 2.2DS-RNA, RNA immunoprecipitation revealed that 2.2DS-RNA interacted with the TATA-binding protein (TBP) and that nucleotides 432 to 832 of 2.2DS-RNA were required for efficient TBP binding. Immunofluorescence experiments showed that 2.2DS-RNA colocalized with cytoplasmic TBP and the stress granule components, G3BP and poly(A)-binding protein 1 (PABP1), in Huh7 cells. In conclusion, our study reveals that 2.2DS-RNA acts as a repressor of HBV transcription through an interaction with TBP that induces stress granule formation. The expression of 2.2DS-RNA may be one of the viral factors involved in viral replication, which may underlie differences in clinical outcomes of liver disease and responses to interferon alpha therapy between patients infected with different HBV genotypes.

IMPORTANCE

Patients infected with certain genotypes of HBV have a lower risk of hepatocellular carcinoma and exhibit a more favorable response to antiviral therapy than patients infected with other HBV genotypes. Using cultured human hepatoma cells as a model of HBV infection, we found that the expression of 2.2DS-RNA caused a decrease in HBV replication. In cultured cells, the ectopic expression of 2.2DS-RNA obviously reduced the intracellular levels of HBV mRNAs. Our analysis of the 2.2DS-RNA-mediated suppression of viral RNA expression showed that 2.2DS-RNA inhibited transcription via binding to the TATA-binding protein and stress granule proteins. Our findings suggest that the 2.2DS-RNA acts as a suppressive noncoding RNA that modulates HBV replication, which may in turn influence the development of chronic hepatitis B.

Effect of hepatitis B virus genotypes on the efficacy of adefovir dipivoxil antiviral therapy

BACKGROUND

Hepatitis B is a common infectious disease in China. Many studies have shown that the genotype of hepatitis B virus (HBV) is probably associated with the efficacy of some antiviral drugs such as interferon α (IFN-α) and Lamivudine (LAM). However, the association between HBV genotype and adefovir dipivoxil (ADV) is controversial. ADV is the most popular antiviral drug in China due to its low price, good antiviral efficacy, few side effects, and convenient of administration.

OBJECTIVES

This study focused on the effect of HBV genotypes on antiviral efficacy of ADV in patients with chronic hepatitis B infection (CHB).

PATIENTS AND METHODS

A total of 526 HBeAg-positive patients with CHB were randomly allocated into two groups. One group took ADV and another group took placebo. Nested Polymerase Chain Reaction (PCR) with multiple pairs of genotype-specific primers (nPCR-MPP) was used to analyze genotypes of HBV in these patients. Antiviral efficacy after treatment for three, six, 12 months was compared among the patients with different HBV genotypes.

RESULTS

Genotype B (73.6%) and genotype C (26.4%) were detected in these patients. After treatment for 12 months, the rate of HBV DNA seroclearance, ALT normalization, and HBeAg seroconversion were significantly higher in ADV group than in placebo group (P < 0.05). However, there were no significant differences in these three rates between patients infected with genotype B and C (P > 0.05).

CONCLUSIONS

HBV genotypes B and C have no significant difference in virologic, biochemical, and immunologic response to ADV.

Susceptibility of different hepatitis B virus isolates to interferon-alpha in a mouse model based on hydrodynamic injection

Interferon alpha (IFN-α) is commonly used for the treatment of chronic hepatitis B (CHB) patients. Many factors including viral genetics may determine the outcome of IFN-α therapy. In this study, we tested whether the expression of IFN-α directly in the liver inhibits HBV gene expression and replication using a HBV hydrodynamic injection (HI) mouse model. Two replication-competent clones from different HBV isolates that belonging to HBV genotype A and B based on a pAAV vector (pAAV-HBV-A and pAAV-HBV-B) were compared for their susceptibility to IFN-α. HBV clones were injected into mice either alone or in combination with a murine (m) IFN-α expression plasmid (pmIFN-α). HBsAg and HBeAg concentrations and HBV DNA levels in mice differed after injection of these two HBV clones. Co-application of pmIFN-α together with the two distinct isolates resulted in markedly different kinetics of decline of HBsAg, HBeAg, and HBV DNA levels in the mice. Immunohistochemical staining of liver sections with anti-HBc showed that mIFN-α application completely inhibited the expression of HBcAg in mice inoculated with pAAV-HBV-B, whereas the expression of HBcAg was only reduced in mice with pAAV-HBV-A. Consistently, mice injected with pAAV-HBV-B and pmIFN-α showed higher expression levels of the IFN-stimulated genes (ISGs) ISG15, OAS, PKR as well as proinflammatory cytokine IL-6 in the liver. In addition, expression levels of anti-inflammatory cytokine IL-10 was down-regulated significantly in liver of the mice injected with pAAV-HBV-B and pmIFN-α. Our data demonstrate that IFN-α exerts antiviral activity in HBV mouse model, but different HBV isolates may have diverse susceptibility to IFN-α.

Clearance of hepatitis B surface antigen during long-term nucleot(s)ide analog treatment in chronic hepatitis B: results from a nine-year longitudinal study

BACKGROUND

Clearance of hepatitis B surface antigen (HBsAg) is considered the ultimate goal in chronic hepatitis B treatment. One treatment option is long-term nucleot(s)ide analog (NA) therapy. We followed a group of long-term NA therapy patients to evaluate the efficacy of this treatment in promoting clearance and longitudinal declines of HBsAg.

METHOD

The study included 791 NA therapy patients who received lamivudine as their first drug. At the baseline, 442 patients were hepatitis B e antigen (HBeAg)+ and 349 were HBeAg-. All analyses were performed after separating the HBeAg+ and HBeAg- cohorts. Cox proportional hazards models were used to determine which factors were associated with HBsAg clearance.

RESULTS

HBsAg clearance was observed in 18 (4.1 %) of the HBeAg+ patients and 20 (5.7 %) of the HBeAg- patients at baseline, giving seroclearance rates of 6.4 and 6.9 %, respectively, over the nine-year study period. HBsAg clearance was influenced by several independent factors that varied according to HBeAg cohort. For HBeAg+ patients, these included previous interferon therapy, infection with hepatitis B virus (HBV) genotype A, a ≥0.5 log IU/mL decline in HBsAg level within six months, and clearance of HBeAg at six months. For HBeAg- patients, these included infection with HBV genotype A, decline in HBsAg at six months, and a baseline HBsAg level of <730 IU/mL.

CONCLUSION

This study suggests that both direct antiviral potential and host immune response are needed to achieve HBsAg clearance by NA therapy. Viral genotype strongly influenced HBsAg clearance during NA therapy.

One single nucleotide difference alters the differential expression of spliced RNAs between HBV genotypes A and D

Hepatitis B virus (HBV) is generally classified into eight genotypes (A to H) based on genomic sequence divergence. The sequence variation among the different HBV genotypes suggests that the spliced RNAs should be different from genotype to genotype. However, the cis-acting element involved in the modulation of the distinct expression profiles of spliced HBV RNAs remains unidentified. Moreover, the biological role of splicing in the life cycle of HBV is not yet understood. In this study, spliced RNAs generated from genotypes A and D were carefully characterized in transfected HepG2 cells. The species and frequency of the spliced RNAs were dramatically different in the two genotypes. Of note, a population of multiply spliced RNAs with intron 2067-2350 excision was identified in HBV genotype A-transfected HepG2 cells, but not in genotype D transfected HepG2 cells. Further, we found a single nucleotide difference (2335) located within the polypyrimidine tract of the splice acceptor site 2350 between the two genotypes, and a single base substitution at 2335 was able to convert the splicing pattern of genotype D (or genotype A) to that of genotype A (or genotype D). These findings suggest that different unique splice sites may be preferentially used in different HBV genotypes resulting in distinct populations of spliced RNAs. The possible significance of the distinct spliced RNAs generated from the different HBV genotypes in HBV infection is discussed.

Does genotype predict response to treatment in children infected with hepatitis B perinatally?

HBV genotype may correlate with outcome and treatment response. Genotype has been compared with treatment response in children infected perinatally with hepatitis B following treatment with oral antiviral drugs (lamivudine or adefovir) or interferon (IFN) alone and with prednisolone priming (Pred/IFN). All children who took part in clinical trials in this unit since 1990 were included. Hepatitis B genotypes were determined by direct sequencing or using a commercial line probe assay (InnoLipa). Sixty-five children were included; 20 were treated with IFN; 19 with Pred/IFN; 22 with lamivudine and 7 with adefovir, some took part in more than one treatment study. 63 out of 65 children were clearly typed into single genotypes; 16, 7, 3, and 37 typing as A, B, C, and D respectively. The majority of South-Asian children had genotype D and European and Afro-Caribbean children were more likely to have genotype A. Treatment response (seroconversion from HBeAg to Anti-HBe) was better in children with genotypes A [n = 16] and D [n = 37] (55.5% and 48.7%), compared to those with B [n = 7] and C [n = 3] (12.5% and 0%) for all treatments. The response to interferon alone was better in children with genotype A compared to D (50% and 36%), but prednisolone priming improved the response so that there was no difference between genotypes A and D (66.7% and 70%). Assessment of genotype in children pre-treatment may provide a guide to potential response. The response to treatment by genotype should be evaluated in future clinical trials in children.

Presence of precore and core promoter mutants limits the probability of response to peginterferon in hepatitis B e antigen-positive chronic hepatitis B

Peginterferon (PEG-IFN) treatment of hepatitis B e antigen (HBeAg)-positive chronic hepatitis B (CHB) results in HBeAg loss in 30% of patients, but clearance of hepatitis B virus (HBV) DNA and hepatitis B surface antigen (HBsAg) from serum is less often achieved. We investigated whether the presence of precore (PC) and basal core promoter (BCP) mutants before PEG-IFN treatment affects serological and virological response. A total of 214 HBeAg-positive CHB patients treated with PEG-IFN ± lamivudine for 52 weeks in a global randomized trial were classified at baseline as wildtype (WT) or non-WT (detectable mutants at PC/BCP) by line-probe assay. Response was assessed at 6 months posttreatment and through long-term follow-up (LTFU). Mutants were detected in 64% of patients, in varying frequencies across HBV genotypes A through D. Patients with WT had higher baseline HBV DNA, HBeAg, and HBsAg levels than patients with non-WT. Patients with WT were more likely to achieve HBeAg loss with HBV DNA <10,000 copies/mL (response, 34 versus 11%, P < 0.001) and HBsAg clearance (18 versus 2%, P < 0.001) at week 78 than non-WT patients. Among WT patients who achieved HBeAg clearance at week 78, 78% had undetectable HBV DNA and 61% achieved HBsAg clearance at LTFU (versus 26% and 15% in non-WT patients, P < 0.001 for both). The presence of WT virus at baseline was an independent predictor of response (odds ratio [OR] 2.90, 95% confidence interval [CI]: 1.15-7.31, P = 0.023) and HBsAg clearance (OR 5.58, 95% CI: 1.26-24.63, P = 0.013) and patients with non-A genotypes with detectable mutants had a low probability of response.

CONCLUSION

The presence of only WT virus at baseline is a strong predictor of response (HBeAg loss with HBV DNA <10,000 copies/mL) to PEG-IFN for HBeAg-positive CHB. Patients with detectable PC and/or BCP mutants have a lower probability of response and are less optimal candidates for PEG-IFN therapy.

Kinetics of hepatitis B surface and envelope antigen and prediction of treatment response to tenofovir in antiretroviral-experienced HIV-hepatitis B virus-infected patients

OBJECTIVE

Hepatitis B surface (HBsAg) and envelope (HBeAg) antigen loss are the primary goals of treating chronic hepatitis B virus (HBV). Although their quantification is useful for other antivirals, such has not been the case with tenofovir disoproxil fumarate (TDF), particularly in HIV infection.

DESIGN

Prospective, multicenter, cohort study in 143 antiretroviral-experienced HIV-HBV-co-infected patients initiating TDF.

METHODS

HBsAg (IU/ml) and HBeAg levels (S/CO) were measured every 6 months. HBsAg and HBeAg decline (Δ) were assessed by mixed-effect linear models. Quantification criteria were used to assess predictability of antigen loss with time-dependent receiver operating characteristic curves.

RESULTS

After a median follow-up of 30.3 months, cumulative incidence rate of HBsAg loss was 4.0% (n = 4) in the entire study population and HBeAg loss was 21.0% (n = 17) in the 96 HBeAg-positive patients. ΔHBsAg was steady during follow-up (HBeAg-positive: -0.027; HBeAg-negative: -0.017 log(10) IU/ml per month), whereas ΔHBeAg ratio was strongly biphasic (-27.1 S/CO per month before and -6.5 S/CO per month after 18 months). Baseline HBeAg and ΔHBeAg were significantly different in patients harboring precore mutations (P < 0.01), whereas both ΔHBsAg and ΔHBeAg were significantly slower among HBeAg-positive patients with CD4(+) T-cell count less than 350 cells/μl (P < 0.05). HBeAg-ratio of 10 S/CO or less at 12 months of therapy was the optimal marker of HBeAg loss, with high sensitivity (0.82) and specificity (0.84) at 36 months. In patients with HBsAg loss, three of four (75.0%) patients had a baseline level of HBsAg of 400 IU/ml or less.

CONCLUSION

During TDF treatment, HIV-induced immunosuppression and HBV genetic variability are associated with differences in HBsAg and HBeAg decline among antiretroviral-experienced, co-infected patients. Considering the decline of HBsAg level is slow, further evaluation is needed to determine its role as a marker of therapeutic efficacy.

Antiviral therapies: focus on hepatitis B reverse transcriptase

Hepatitis B virus (HBV) is the etiologic agent of mankind's most serious liver disease. While the availability of a vaccine has reduced the number of new HBV infections, the vaccine does not benefit the approximately 350 million people already chronically infected by the virus. Most of the drugs approved by the FDA for the treatment of hepatitis B target the reverse transcriptase (RT or P gene product) and are nucleoside RT inhibitors (NRTIs) that suppress viral replication. However, prolonged monotherapies directed against a single target result in the emergence of viral resistance. HBV genotypic differences affect NRTI resistance, and because the reading frames of the S (surface antigen) and P genes partially overlap, genomic differences that affect the surface of the virus may also alter the viral polymerase sequence, function and drug susceptibility. The scope of this review is to assess the effects of HBV genotypic variation on the development of drug resistance to NRTIs. Some RT residues that vary among different genotypes are in the vicinity of residues that mutate and give rise to NRTI resistance. Interactions between these amino acids can help explain the effect of HBV genotype on the development of NRTI resistance during antiviral therapies, and might help in the design of improved therapeutic strategies.

Is response to antiviral treatment influenced by hepatitis B virus genotype?

Recently released clinical practice guidelines and consensus conference statements point to the importance of hepatitis B virus (HBV) genotyping in therapeutic algorithms for the treatment of chronic hepatitis B. This information usually comes from post hoc analyses of clinical trials which were not designed to study associations with the HBV genotype. We have performed a literature search through to April 2009 and have selected randomized clinical trials of currently approved anti-HBV drugs providing information on HBV genotypes and (i) baseline characteristics of study subjects, (ii) any response to antiviral therapy, (iii) interaction between HBV genotypes and the type of therapy. There were several intrinsic features and weaknesses in the majority of clinical trials conducted so far which make it difficult to reach firm conclusions about the role of HBV genotypes in response to antiviral therapy. Indeed, most trials were necessarily multicenter in order to reach a sufficient statistical power, but pooling together patients of different ethnicities may have revealed false-positive associations between response to antiviral therapy and HBV genotype. Moreover, endpoint definitions, especially for the composite ones, varied substantially among studies, leading to lack of homogeneity. Finally, possible interactions between the type of therapy and the HBV genotype were only seldom analysed. The present review highlights several caveats regarding current indications proposed by the major clinical practice guidelines and consensus conference statements published thus far and emphasise the need for further long term studies in the field.

Does RNA interference provide new hope for control of chronic hepatitis B infection?

Hepatitis B virus (HBV) infection is a global human health problem, with an estimated 350 million people having chronic hepatitis B (CHB) infection worldwide. The majority of infections acquired during adulthood are resolved without intervention; however, infections acquired at birth or during early childhood have a 90% chance of progressing to CHB, leading to a host of adverse effects on the liver, including cirrhosis and cancer. CHB is currently treated with a combination of cytokines and/or nucleoside/nucleotide analogues; however, adverse side effects to cytokine therapy and the selection of resistance mutations to nucleoside analogues often abrogate the efficacy of treatment. The recent discovery that small interfering RNA and microRNA are active in mammalian cells suggests it might be possible to supplement existing HBV therapies with small RNA-based therapeutic(s).

Influence of genotype on hepatitis B surface antigen kinetics in hepatitis B e antigen-negative patients treated with pegylated interferon-alpha2a

BACKGROUND

The aim of this study was to assess the influence of hepatitis B virus (HBV) genotypes on serum hepatitis B surface antigen (HBsAg) kinetics in hepatitis B e antigen (HBeAg)-negative patients treated with pegylated interferon-alpha2a (PEG-IFN-alpha2a).

METHODS

A total of 48 consecutive patients treated with PEG-IFN-alpha2a (180 microg/week) for 48 weeks were assessed. HBV genotype was determined. Serum HBV DNA and HBsAg were assessed at baseline, during treatment (weeks 12, 24 and 48) and during follow-up (weeks 72 and 96).

RESULTS

The distribution of HBV genotype was A 27%, B 17%, C 12%, D 29% and E 14%. Mean +/-sd pretreatment serum HBV DNA (6.9 +/-1.5 log(10) copies/ml) was not different between genotypes and decreased under treatment in all genotypes without significant difference. Mean +/-sd pretreatment serum HBsAg (3.6 +/-0.6 log(10) IU/ml) was significantly different between genotypes (P<0.001), with high levels in genotypes A and C, intermediate levels in genotypes D and E, and low levels in genotype B (4.0 +/-0.3, 4.1 +/-0.7, 3.6 +/-0.5, 3.6 +/-0.4 and 2.7 +/-0.6 log(10) IU/ml, respectively). Serum HBsAg decreased under treatment in all genotypes with a significant difference. At the end of treatment, mean +/-sd decrease was high in genotype A, intermediate in genotypes B and D, and low in genotypes C and E (1.3 +/-1.6, 0.7 +/-0.7, 0.6 +/-0.9, 0.4 +/-1.0 and 0.4 +/-0.9 log(10) IU/ml, respectively; P<0.001). During follow-up, serum HBsAg continued to decrease in genotypes A and D, whereas rebound was observed in genotypes B, C and E.

CONCLUSIONS

HBV genotype has a strong influence on serum HBsAg kinetics during PEG-IFN-alpha2a therapy in HBeAg-negative patients.

Prediction of response to treatment of chronic hepatitis B with pegylated interferon in the Philippines

The response marker for interferon has not been investigated fully for hepatitis B viruses (HBVs) in the Philippines where novel subtypes B5 and C5 were recognized recently. The prediction parameters for interferon treatment were assessed, with emphasis on the mutation patterns in the basal core promoter and precore regions in patients with chronic hepatitis B. Seventeen HBeAg-positive patients were stratified according to response to treatment with pegylated interferon based on HBe seroconversion and HBV load. Intra-patient distributions of wild-type strains (A1762, G1764) and variants (T1762, A1764) were analyzed using HBV-DNA amplification and subsequent molecular cloning. The rate of variants (T1762, A1764) harbored by a patient was higher among responders (41.2% and 31% per person on average) than among non-responders (2.4% and 2.4%) to treatment with pegylated interferon at the baseline, respectively (P < 0.05). The rate of variants (T1762, A1764) harbored by responders (41.2% and 31%) decreased to 1.7% and 1.7%, and wild-type strains (A1762, G1764) conversely became majority (98.3% and 98.3%) after treatment with pegylated interferon, respectively. HBV strains harbored by two of six responders and a patient with lower baseline load (1.0 x 10(4) copies/ml) showed genotype shift from A to other genotypes, where genotype A disappeared preferentially after the loss of HBeAg and genotypes B and C formed a major population. These results suggest that the HBV variants (T1762, A1764) and HBV genotype A in the Philippines have an advantage in the response to pegylated interferon. These results warrant a large-scale examination for further precise prediction of the response to treatment with interferon.

Response to antiviral treatment in patients infected with hepatitis B virus genotypes E-H

No data on antiviral response of HBV genotypes E-H are available so far although these HBV genotypes contribute significantly to the global HBV burden. Of 49 patients with HBV genotypes E-H, 23 received interferon (IFN)-alpha, 12 nucleos(t)ide analogues and 14 patients were untreated. HBV genotype was determined by direct sequencing of the HBV S gene. Sustained virological response in IFN-treated patients was defined as normalization of ALT and decrease of HBV-DNA <4,000 IU/ml 6 months after treatment. Virological response with nucleos(t)ide analogues was assumed in patients with a HBV-DNA <200 IU/ml after 48 weeks of treatment. HBV genotype E was found in 61.2% (n = 30), HBV genotype F in 8.2% (n = 4), HBV genotype H in 10.2% (n = 5) of patients. Among patients with HBV genotype G (20.4%; n = 10) there were four HBV genotype G/A and three HBV genotype G/C co-infections. Patients had Caucasian (43%), African (55%), or Asian (2%) background. End of treatment response was 70% (16/23) and sustained virological response was 35% (8/23) for patients treated with IFN-alpha. Sustained virological response was 36% for HBV genotype E (n = 5/14), 50% for HBV genotype F or H (n = 2/4), and 20% for HBV genotype G (n = 1/5). Virus suppression at week 48 was achieved in 67% of patients treated with nucleos(t)ide analogues. According to the present preliminary data HBV genotypes E, F, and H appear to be sensitive to IFN-alpha. Lower rates of response to IFN-alpha in patients with HBV genotype G might be related to the frequent occurrence of double infection.

Early HBeAg loss during peginterferon alpha-2b therapy predicts HBsAg loss: results of a long-term follow-up study in chronic hepatitis B patients

OBJECTIVES

Treatment with pegylated interferon (PEG-IFN) alpha-2b results in hepatitis B e antigen (HBeAg) loss in 36% of patients at 6 months post treatment. The aim of this study was to determine whether a long-term response to PEG-IFN is dependent on the timing of HBeAg loss.

METHODS

A total of 91 patients treated with PEG-IFN alpha-2b alone (100 microg per week) and 81 patients treated with PEG-IFN alpha-2b and lamivudine (100 mg/day) for 52 weeks were enrolled in this study. Patients were initially followed up at 4-week intervals and had one additional long-term follow-up (LTFU) visit (mean: 3.03+/-0.77 years 26 weeks post treatment).

RESULTS

Of the 172 patients included, 78 patients (46%) did not have loss of HBeAg, 47 (27%) lost HBeAg within 32 weeks, and 47 patients (27%) had loss of HBeAg after week 32. At LTFU, patients with HBeAg loss< or =32 weeks had hepatitis B virus DNA of <400 copies/ml significantly more often than did those who lost HBeAg after week 32 (47 vs. 21%, respectively; P=0.009). Hepatitis B surface antigen (HBsAg) negativity was also observed significantly more often in patients with early HBeAg loss (36 vs. 4%, respectively, P<0.001). Early HBeAg loss tended to occur more often in patients treated with PEG-IFN and lamivudine combination therapy than in those treated with PEG-IFN alone (35 vs. 21%; P=0.10), as did HBsAg loss (15 vs. 8%; P=0.14).

CONCLUSIONS

Early PEG-IFN-induced HBeAg loss results in a high likelihood of HBsAg loss and may be associated with more profound viral suppression during the first 32 weeks of therapy in patients treated with lamivudine combinations.

Low pretreatment serum HBsAg level and viral mutations as predictors of response to PEG-interferon alpha-2b therapy in chronic hepatitis B

BACKGROUND

Viral genomic mutations have become increasingly recognized as being associated with the outcome of chronic HBV infection. However, the role of viral mutations as a predictor of response to pegylated-interferon (PEG-IFN) therapy has so far remained unclear.

STUDY DESIGN

Viral mutations in the enhancer II/basal core promoter (BCP)/precore and the pre-S regions were characterized by direct sequencing in pretreatment serum samples of 50 patients with chronic hepatitis B (33 HBeAg-positive and 17 HBeAg-negative), who were treated for 48 weeks with PEG-IFN alpha-2b.

RESULTS

Sustained virological response at 48 weeks post treatment, defined as HBeAg seroconversion and HBV DNA<2000IU/mL for HBeAg-positive patients, and HBV DNA<200IU/mL for HBeAg-negative patients, was achieved in 12 (36.4%) and 6 (35.3%) of HBeAg-positive and HBeAg-negative patients, respectively. Response to PEG-IFN therapy correlated to low pretreatment HBsAg level but did not correlate with HBV genotype, pretreatment alanine transaminase and HBV DNA levels. In HBeAg-positive hepatitis, PEG-IFN response correlated with the appearance of double BCP mutations (A1762T/G1764A) at baseline (P=0.041). In the HBeAg-negative group, response to PEG-IFN therapy was associated with the presence of pre-S mutation/deletions (P=0.028). Multivariate analysis identified low pretreatment HBsAg level as an independent factor associated with SVR in both groups.

CONCLUSIONS

Pretreatment quantitative HBsAg determination is useful for predicting response to PEG-IFN therapy. The presence of double BCP and pre-S mutation/deletions at entry may be associated with a high rate of antiviral response in HBeAg-positive and HBeAg-negative hepatitis, respectively.

Meta-analysis: the effect of interferon on development of hepatocellular carcinoma in patients with chronic hepatitis B virus infection

PURPOSE

In patients chronically infected with hepatitis B virus, interferon has been used for the purpose of viral suppression by loss of hepatitis B e antigen (HBeAg) with or without seroconversion to antibody to HBeAg (anti-HBe). However, discussion about the effect of interferon on the development of hepatocellular carcinoma (HCC) has been controversial.

METHODS

We conducted a meta-analysis of published studies. Eight studies were retrieved (1,303 patients), including two randomized controlled trials (RCTs) and six non-RCTs (553 patients received interferon treatment).

RESULTS

The pooled estimate of the preventive effect of treatment was significantly in favor of interferon (risk difference -5.0%; 95% CI -9.4 to -0.5, P = 0.028). By subgroup analyses, the preventive effect of interferon treatment was shown in the Asian population (risk difference -8.5%; 95%CI -13.6 to -3.6, P = 0.0012), the population with the incidental rate of HCC >or=10% if untreated with interferon (risk difference -9.4%; 95%CI -14.2 to -4.6, P = 0.0001), and the population with the proportion of HBeAg-positive patients to the study population >or=70% (RD -6.0%; 95%CI -11.8 to -0.2, P = 0.043). However, the preventive effect of interferon was not shown in the European population, the population with a lower incidental rate of HCC if untreated with interferon, and the population with the lower proportion of HBeAg-positive patients to the study population. An evaluation using the Begg method indicated no evidence of publication bias.

CONCLUSIONS

Interferon treatment is considered to restrain HCC development in patients with chronic hepatitis B virus infection, especially in HBeAg-positive Asians.

Benefits and risks of interferon therapy for hepatitis B

Alpha interferon is the only licensed drug for hepatitis B with immunomodulatory as well as viral inhibitory properties. Potential advantages of interferon compared to nucleoside analogs include a lack of drug resistance, a finite and defined treatment course, and a higher likelihood for hepatitis B surface antigen (HBsAg) clearance. Approximately 30% of hepatitis B e antigen (HBeAg)-positive and 40% of HBeAg-negative cases have a sustained virological response (when defined as HBeAg seroconversion and/or hepatitis B virus (HBV) DNA levels below 20,000 copies/mL, respectively) 6 months after completion of a 48-week course of peginterferon alfa-2a These responses remain durable in 80% and 50% of cases, respectively, when evaluated several years later. Recent studies have shown that changes in HBsAg and HBeAg concentration during treatment predict sustained virological response and serial monitoring of HBsAg is helpful in predicting HBsAg clearance. HBeAg-positive patients with genotype A have higher rates of HBeAg and HBsAg clearance, whereas HBeAg-negative patients with genotype D have the lowest rate of response to interferon therapy. Long-term follow-up of virological responders to either standard alpha interferon or peginterferon has demonstrated a progressive increase in the rate of HBsAg clearance, particularly in patients who were initially HBeAg-positive. Future studies need to address if specific virological benchmarks during therapy can be used to tailor treatment duration.

CONCLUSION

Peginterferon alfa has a place as first-line therapy of hepatitis B in patients who are carefully selected on the basis of pretreatment serum HBV DNA and aminotransferase levels, safety considerations, and viral genotype.

Characterization of genotype-specific carboxyl-terminal cleavage sites of hepatitis B virus e antigen precursor and identification of furin as the candidate enzyme

Hepatitis B e antigen (HBeAg) is a secreted version of hepatitis B virus (HBV) core protein that promotes immune tolerance and persistent infection. It is derived from a translation product of the precore/core gene by two proteolytic cleavage events: removal of the amino-terminal signal peptide and removal of the carboxyl-terminal arginine-rich sequence. Four RXXR motifs are present at the carboxyl terminus of the HBeAg precursor, with the first two fused as (151)RRGRSPR(157). Genotype A possesses two extra amino acids at the first motif ((151)RRDRGRSPR(159)), which weakens the first motif and separates it from the second one. Western blot analysis of patient sera revealed a single HBeAg form for genotypes B to D but two additional forms of larger sizes for genotype A. Site-directed mutagenesis and transfection experiments with human hepatoma cell lines indicated that HBeAg of genotype B is derived from cleavage at the first ((151)RRGR(154)) motif. The major HBeAg form of genotype A corresponds to cleavage at the second ((156)RSPR(159)) motif, and the other two forms are cleavage products of the first ((151)RRDR(154)) and third ((166)RRRR(169)) motifs, respectively. Only the cleavage product of the third motif of genotype A was observed in furin-deficient LoVo cells, and an inhibitor of furin-like proprotein convertases blocked cleavage of the first and second motifs in human hepatoma cells. In conclusion, our study reveals genotypic differences in HBeAg processing and implicates furin as the major enzyme involved in the cleavage of the first and second RXXR motifs.

Hepatitis B therapy in children

Chronic hepatitis B virus (HBV) infection is a major cause of liver disease throughout the world, leading to cirrhosis and hepatocellular carcinoma in many individuals. Children are more likely to develop chronic HBV infection as they demonstrate greater immunotolerance to the virus, and response to therapy in children remains disappointing. Three therapeutic agents for chronic HBV infection in children have been approved in the USA, including standard IFN-alpha, lamivudine and adefovir. IFN-alpha has been the most effective ( approximately 30% hepatitis B e antigen [HBeAg] seroconversion; 10% hepatitis B surface antigen [HBsAg] seroconversion), although benefits are primarily observed in children with alanine aminotransferase levels over two-times the upper limit of normal and must be weighed against significant side effects. Studies comparing the long-term outcome of chronic hepatitis B in children treated with IFN-alpha and in untreated controls show that the rate of anti-HBeAb seroconversion tends to overlap in treated and untreated patients within a few years of follow-up, suggesting that IFN-alpha simply accelerates a spontaneous event. Lamivudine's virologic response rates mirror those of IFN-alpha (23-31% HBeAg seroconversion) with easier administration and a better safety profile but lower HBsAg seroconversion (2-3%) and high rates of drug resistance. Adefovir data show low rates of resistance and a good safety profile, but virologic response was limited to adolescent patients and was lower than that of lamivudine (16% HBeAg seroconversion; <1% HBsAg seroconversion). Entecavir and tenofovir, both approved therapies for adults with chronic HBV infection, are in trials for use in children. Future therapies will probably include these agents as well as combined therapies. Finally, watchful waiting of children is an option since current therapies are only 30% effective at best, although the long-term impact of therapy in childhood on rates of cirrhosis and hepatocellular carcinoma remains unknown.

Genetic Variability of Hepatitis B virus and Response to Antiviral Therapy

Hepatitis B virus (HBV) infection is a global health issue. Effective and individualized treatment of chronic hepatitis B to prevent progression to end-stage liver diseases and hepatocellular carcinoma is needed. HBV can be classified into eight genotypes (A–H) on the basis of genome sequence divergence. In addition, several naturally occurring HBV mutants have also been identified. The epidemiology of HBV genotypes and their implications for response to antiviral therapy have become increasingly recognized. Recent studies suggested that responses to standard interferon treatment in patients with genotype A or B are better than those with genotype C or D; however, conflicting results exist regarding the response to pegylated interferon. The influence of dose and duration on interferon-based therapy remains to be clarified. In addition to genotype, naturally occurring mutations such as precore and core promoter mutations have also attracted much attention, because they have been shown to affect the disease progression of HBV-related chronic liver disease and possibly the response to antiviral therapy. Here, we review the differences in antiviral theraputic response among HBV genotypes and discuss the role of precore or core promoter mutations in response to antiviral therapy.

Reviews for APASL guidelines: immunomodulator therapy of chronic hepatitis B

The primary aim of immunomodulator therapy is to help the natural human immune system to mount a defense against hepatitis B virus. IFN-alpha has been used for the treatment of HBeAg-positive and HBeAg-negative chronic hepatitis B for over two decades and has been shown to be effective in suppressing HBV replication and in inducing serological response leading to long-term clinical benefits. IFN-alpha has been used in patients with well-compensated cirrhosis with comparable or better response to that in non-cirrhotic patients. IFN-alpha therapy in patients with cirrhosis has a similar side effect profile as in those without cirrhosis. However, IFN-alpha is contraindicated in patients with overt or decompensated cirrhosis. Pegylated IFN-alpha has been shown to be effective in treatment of chronic hepatitis B with sustained response rate in about one-third of the treated patients. Peg IFN-alpha treatment in non-responders to lamivudine or adefovir dipivoxil showed similar response rate to that seen in naïve patients. Thymosin alpha(1) is effective in treatment of HBeAg-positive and HBeAg-negative chronic hepatitis B with a significantly increasing virological response over time after therapy.

Effect of β-L-D4A on human DNA polymerases β and δ and its mechanism

AIM: To purify and characterize the DNA polymerase δ and investigate the side effects of β-L-D4A (a novel nucleoside analog) on human DNA polymerases β and δ.

METHODS: Human DNA polymerase δ was separated from crude extract of human Hela cells by ion exchange chromatography. Detailed kinetic parameters were determined for β-L-D4A against DNA polymerases β and δ.

RESULTS: Human DNA polymerase δ was purified and characterized with a yield of 15% and a specific activity of 1911 Ukat/mg. When β-L-D4A was used as an inhibitor, the kinetic parameters of human DNA polymerases β and δ were Km = 1.86 μmol/L and 2.45 μmol/L, IC₅₀ = 25.21 μmol/L and 150.1 μmol/L, Ki = 24.03 μmol/L and 132.7 μmol/L, respectively, suggesting that the inhibitory effect of β-L-D4A on human DNA polymerases β and δ was less than that of lamivudine.

CONCLUSION: β-L-D4A is a competitive inhibitor of DNA polymerases β and δ. Its toxic side effects on DNA polymerases β and δ are less than lamivudine. It can be expected to become a high efficient and low toxic anti-HBV agent.

Effect and mechanism of β-L-D4A on DNA polymerase α

AIM: To investigate the safety of β-L-D4A on DNA polymerase α.

METHODS: Ion exchange chromatography was used to separate DNA polymerase α from crude extract of human Hela cells. Detailed kinetic parameters were determined for β-L-D4A against DNA polymerase α.

RESULTS: DNA polymerase α was purified with 4% yield and 31 000 units/mg specific activity. The Michaelis constant (Km = 3.22 μmol/L), 50% inhibition concentration (IC50 = 178.49 μmol/L) and inhibition constant (Ki = 126 μmol/L) of β-L-D4A were determined by kinetic analysis.

CONCLUSION: β-L-D4A is a more safe nucleoside for hepatitis B virus (HBV) infection with a lower host toxicity.

Role of viral factors in the natural course and therapy of chronic hepatitis B

Hepatitis B virus (HBV) infection is a global health problem that causes a wide spectrum of liver disease, including acute or fulminant hepatitis, inactive carrier state, chronic hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). The pathogenesis of hepatocyte damage associated with HBV is mainly through immune-mediated mechanisms. On the basis of the virus and host interactions, the natural history of HBV carriers who are infected in early life can be divided into four dynamic phases. The frequency, extent, and severity of hepatitis flares or acute exacerbation in the second immune clearance and/or fourth reactivation phase predict liver disease progression in HBV carriers. In the past decade, hepatitis B viral factors including serum HBV DNA level, genotype, and naturally occurring mutants predictive of clinical outcomes have been identified. The higher the serum HBV DNA level after the immune clearance phase, the higher the incidence of adverse outcomes over time. In addition, high viral load, genotype C, basal core promoter mutation, and pre-S deletion correlate with increased risk of cirrhosis and HCC development. As to the treatment of chronic hepatitis B, patients with high HBV DNA level and genotype C or D infection are shown to have a worse response to interferon therapy. In conclusion, serum HBV DNA level, genotype, and naturally occurring mutants are identified to influence liver disease progression and therapy of chronic hepatitis B. More investigations are needed to clarify the molecular mechanisms of the viral factors involved in the pathogenesis of each stage of liver disease and the response to antiviral treatments.